VSTO Excel Worksheet Scrolling Event

How about leveraging System.Windows.Forms.Timer alongside some conditions to determine when the user stops scrolling, without relying purely on timers:

• Hook into the scrolling messages to detect when scrolling starts.
• Start a System.Windows.Forms.Timer to check for the scrolling state at intervals.
• If no scrolling is detected for a specific duration, consider it as the end of scrolling.

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;

public class ScrollDetector
{
    private const int WM_HSCROLL = 0x0114;
    private const int WM_VSCROLL = 0x0115;
    private const int WM_MOUSEWHEEL = 0x020A;
    private Timer scrollTimer;
    private bool isScrolling;

    public ScrollDetector()
    {
        scrollTimer = new Timer();
        scrollTimer.Interval = 100; // Check every 100ms
        scrollTimer.Tick += ScrollTimer_Tick;
        isScrolling = false;

        // Set up your hook or message intercept here
    }

    private void ScrollTimer_Tick(object sender, EventArgs e)
    {
        if (!isScrolling)
        {
            scrollTimer.Stop();
            OnScrollEnd();
        }
        isScrolling = false;
    }

    private void OnScrollEnd()
    {
        // Handle scroll end event
        Console.WriteLine("Scrolling ended");
    }

    // Example window procedure to intercept scroll messages
    protected override void WndProc(ref Message m)
    {
        if (m.Msg == WM_HSCROLL || m.Msg == WM_VSCROLL || m.Msg == WM_MOUSEWHEEL)
        {
            isScrolling = true;
            if (!scrollTimer.Enabled)
            {
                scrollTimer.Start();
            }
        }
        base.WndProc(ref m);
    }
}